PORTLAND, Ore. — The Rockets had spent the night battling back so often they made it look like some sort of weird, rope-a-dope strategy. It wasn’t.

It might have seemed they were where they wanted to be, leading by four, in the fourth quarter. They weren’t.

The Rockets had rallied back all night, but the same problems that put them in all those holes had not been mastered. So with the Portland Trail Blazers playing for their playoff lives and soaring, the Rockets tripped over themselves until Portland pulled away for an 88-77 win to force Game 6 on Thursday in Toyota Center.

“You got to play with some composure and we didn’t do that, in the fourth quarter especially,” Rockets coach Rick Adelman said. “Early in the game, they tried to push it up and down and we got into a frenzied pace ourselves. We have to have more control and patience than we showed tonight.

“That group we had at the start of the fourth quarter, we just didn’t play with the confidence and the composure you need to play with in the fourth quarter of the game. We just put them on the line. We made some really silly fouls at the start of the fourth quarter. You can’t do that. It’s too tough against a team like that.”

There were corrections to be made. But after Yao Ming scored 15 points on 7-of-12 shooting, there were three he had on the top of his list:

“Get the ball inside. Get the ball inside. Get the ball inside.”

Still, the Rockets could have overcome his lack of deep touches, their turnover problems and the combined 50 points the Blazers got from Brandon Roy and LaMarcus Aldridge.

They had overcome a 10-point lead in the first and second quarters and an 11-point lead in the third quarter, keeping it close and heading into the fourth quarter trailing by just two.

“We knew they were going to come out with this crowd and have a great first quarter,” Shane Battier said. “Our concern was to take their best hit and keep it close. At the end of the first quarter we were close. They opened it up in the second a little bit. We fought back. We knew, once we settled in and played our defense, we’d get back in the game.”

All that went to plan, and when the Rockets opened the fourth quarter with a 7-0 run, they had their largest lead of the game, 68-64. But Yao’s jumper in that run was his last field goal of the game, and it came with 10:19 left. Von Wafer hit a pair of jumpers, his second with 9:35 left for the four-point lead, but they were the Rockets’ last points for more than five minutes.

With the game to be won, the Rockets grew harried and crumbled. Wafer forced a jumper that missed. Ron Artest, who was 3-of-9, turned the ball over and missed a 3-pointer. Yao missed two shots from the perimeter. Wafer had a drive blocked by Greg Oden. Aaron Brooks, who made just six of 20 shots, misfired on a rushed 3.

“I don’t really know what happened out there,” Artest said. “It was weird that they built up so many leads and we kept coming back. Maybe if we just sustained it we could have won by 10. We just couldn’t play a solid game for 48 minutes.”

Worse, while the Rockets’ offense crumbled, the defense made it so easy for the Blazers that Portland did not have to do much.

Carl Landry and Kyle Lowry repeatedly committed needless fouls. After Roy scored with 8:25 remaining, cutting the Rockets’ lead to two, the next foul put the Blazers in the bonus. They scored their next five points from the line.

And when the Rockets did get a stop, Yao slapped the rebound back out to Roy, who passed to Travis Outlaw for a 3-point shot and a 74-68 margin.

By then, the Blazers were rolling. Roy pulled up for another 3, and then scored on a drive, and with 4:49 left, the lead was 79-68, and the Rockets were hurting themselves more than they were the Blazers.

“We really aided their run in the fourth by putting them on the foul line,” Battier said. “They got in the bonus early. That was really the difference in the game. We did a great job in the half court against their offense, but once we put them on the line, they got a rhythm, they got it going.

“We were making so many mistakes, so many bad plays you can’t make on the road and expect to win.

“If we could have kept them off the free-throw line, it’s a much difference game for us. But we couldn’t keep them off the foul line.”

The Rockets had one more run in them. Artest hit a 3-pointer and Luis Scola, who had 21 points, but just six after the first quarter, scored inside.

When Brooks hit a runner, the Rockets were within 80-75 with 2:15 left. But by then, they needed a perfect finish.